This work is intended to explore the observation that many antibiotics which inhibit the translational functions of the bacterial ribosome also prevent its assembly in microbial cells. These antibiotics interact with sequences in the ribosomal RNA in the ribosomal subunits. Studies will be conducted to look at the direct binding of different antibiotics to ribosomal RNA and to subunit precursors in order to explore the mechanism of assembly inhibition. Inhibitory effects of the drugs on the conformational changes in rRNA needed for particle synthesis will also be explored. This work will help define the features of the ribosome structure as a target for antimicrobial agents and will provide information needed for the design of more effective antibiotics.